Early President Washington D858

[BC Coyote]

L1 and L2 are peaked using a 23.5 MHz signal from the signal generator.

I remove the antenna from the radio, put a couple inches of wire in the end of the SO-239 and then set a homemade "relay buzzer" next to it. The buzzer creates a bunch of RF "hash". You can then tweak L1 and L2 for minimum noise.

Of course, if you have all the correct gear to do it properly, by all means use the proper method. But if you don't the "buzzer" method works fine too......

 

[loosecannon]

I have found that the Noise Blankers in the 858 SSB chassis have a night and day difference in performance between when they are aligned with a signal generator set a 23.5mhz as opposed to being tuned by ear.

both methods will get you noise blanking, but they really shine when they are done correctly.

here are some snippets from the TRC-449 service manual (eternal thanks to nomad for giving this to CBtricks) that describe the amplification and AGC portions of the noise blanker circuit.

note that the exact issue being discussed in this thread is mentioned here:




the receiver portion of the alignment is also worth posting here since it mentions not adjusting L2 (i always do though...)


one thing that OP can look for as well is whether or not VR2 has been maxed out.
LC

 

[HavaV10]

I remove the antenna from the radio, put a couple inches of wire in the end of the SO-239 and then set a homemade "relay buzzer" next to it. The buzzer creates a bunch of RF "hash". You can then tweak L1 and L2 for minimum noise.

Of course, if you have all the correct gear to do it properly, by all means use the proper method. But if you don't the "buzzer" method works fine too......

thanks BC for the info. Very interesting.

 

[HavaV10]

I have found that the Noise Blankers in the 858 SSB chassis have a night and day difference in performance between when they are aligned with a signal generator set a 23.5mhz as opposed to being tuned by ear.

both methods will get you noise blanking, but they really shine when they are done correctly.

here are some snippets from the TRC-449 service manual (eternal thanks to nomad for giving this to CBtricks) that describe the amplification and AGC portions of the noise blanker circuit.

note that the exact issue being discussed in this thread is mentioned here:

View attachment 72926
View attachment 72927

the receiver portion of the alignment is also worth posting here since it mentions not adjusting L2 (i always do though...)
View attachment 72928

one thing that OP can look for as well is whether or not VR2 has been maxed out.
LC

I just checked and VR2 is almost maxed out. What is the function of VR2

 

[nomadradio]

the function of VR2

AGC adjustment. See steps 6 and 7 on page 16 of the TRC449 service manual.

73

 

[HavaV10]

AGC adjustment. See steps 6 and 7 on page 16 of the TRC449 service manual.

73

ok thanks

 

[loosecannon]

HavaV10,

You're most likely not going to have the test equipment required to get VR2 set "correctly" but you can most likely just turn it to about half way and you'll know if this was your issue.

the easiest way would be while listening to a SSB signal that is strong enough to cause the distortion and then just back off VR2 slightly to see if it improves.

be sure to make a note about it's original position so you can put it back there if needed.
LC

EDIT: here's the place to find the service manual you're looking for:
www.cbtricks.org

first, click on "Radio Schematics, Manuals, etc." over on the left.
now click on the "Realistic" logo.
now scroll down to where you find the "TRC-449" and click on that.

Voila!
now you've got a whole bunch of info on that radio. well, it's not the exact radio but the PC board inside is the same.
LC

 

[HavaV10]

HavaV10,

You're most likely not going to have the test equipment required to get VR2 set "correctly" but you can most likely just turn it to about half way and you'll know if this was your issue.

the easiest way would be while listening to a SSB signal that is strong enough to cause the distortion and then just back off VR2 slightly to see if it improves.

be sure to make a note about it's original position so you can put it back there if needed.
LC

EDIT: here's the place to find the service manual you're looking for:
www.cbtricks.org

first, click on "Radio Schematics, Manuals, etc." over on the left.
now click on the "Realistic" logo.
now scroll down to where you find the "TRC-449" and click on that.

Voila!
now you've got a whole bunch of info on that radio. well, it's not the exact radio but the PC board inside is the same.
LC

thanks Mr. Loosecannon it's the weaker signals that have the not so clear audio. They sound very choppy and not smooth sounding like they should. I'll mess with it a little. It's working pretty good right now. The (NO ADMIT) sticker is still covering L2 and has never been messed with.